This invention relates to hitch apparatus for connecting or coupling together adjacent ends of two vehicles, particularly vehicles intended to be connected or coupled to other vehicles to form a train of vehicles and also relates to apparatus for measuring the position of one vehicle relative to the position of an adjacent attached vehicle.
For mining applications, it is known to provide a series of conveyors arranged in the form of a train with each conveyor unit being mounted on wheels so the conveyor system can be readily moved. Conveyor systems of this type have been developed for both use in above ground, open pit mines and also for use underground, where the amount of room available for operation of the conveyor system can be quite limited. In order that such conveyor systems can be operated in an efficient manner as the mine is operated and extended, it is desirable to have an efficient and reliable system for steering the train of conveyor vehicles as the train is moved to a new, desired position. In particular it is necessary to maintain the intake end of the conveyor train in position for delivery of ore or other mine material from a mining machine as it moves along the face of the rock or material being mined.
A well known method for mining ore from an open pit mine is to drill and then blast the face of the ore body and then use an expensive shovel excavator to transfer the ore rock or material to very large ore trucks which are also quite expensive. There is a perceived need to replace such an ore delivery system with an efficient mining machine that can deliver the ore or other mine material directly to a readily movable conveyor system that can be kept in position to receive the ore or other material from the mining machine. The movable conveyor system or train can then, if desired, deliver the ore to a long fixed conveyor system. Such a movable conveyor for a mining machine may have several advantages including a reduction in noise and dust, a lower capital cost, and the ability to transfer ore or overburden continuously, thereby improving mining efficiency and rate.
U.S. Pat. No. 5,366,059 issued Nov. 22, 1994, to Prairie Machine & Parts Mfg (1978) Ltd., describes and illustrates a conveyor system adapted for use underground which comprises a plurality of conveyor vehicles connected together in the form of a train and a steering system for steering this train. All but one of the vehicles in the train has a single pair of steerable wheels with the vehicle at the outby end of the train (that is, the end to which the mine material is being delivered) having two pairs of steerable wheels. Hydraulic actuators are used to steer each pair of wheels and there is a control mechanism for controlling and coordinating these actuators in order to set the steering angles of the wheels. This known conveyor system uses a control system that has sensors for determining the current steering angle for each pair of wheels and generating electric signal indicative thereof and memory for storing the signals as the train trams. The distance that the wheels on the train travel is also measured in this known system.
Recent U.S. Pat. No. 7,949,447 issued May 24, 2011 describes a steering system for a plurality of conveyor vehicles arranged in a train, this system being designed for use in an underground mining operation. Each conveyor vehicle has a pair of steerable wheels with the pair at one end being a selective leading pair having its steering angle determined by an operator. An electrical control system automatically steers all the wheels trailing behind the leading pair. Vehicle angle sensors measure intercar angles between adjacent vehicles and provide this information to the control system. The distance traveled by the train is determined and provided to the controller. Wheel angle sensors provide signals indicative of the currents steering angle for each wheel pair and the controller adjusts the actual steering angle to a desired angle by calculating adjustments based on the measurement inputs.
Although these known systems for steering a train of conveyor vehicles are satisfactory, particularly for use in an underground mine, there is a need for an improved system for steering and controlling conveyor vehicles which are adapted for use above ground such as in an open pit mine. In particular, there is a need in the movable conveyor industry for an improved hitch apparatus that can not only connect a steerable, self propelled trailing vehicle to a self propelled leading vehicle but which can also measure the position of the trailing vehicle relative to the leading vehicle in order to provide details of this position to a steering system for the vehicles.